Battery and Electrical Wiring
An overview of all electrical work undertaken in the 2020 refit with links to greater detail is found in the New Wiring section of the Electrical Work Planned for 2020 web page. Many of the links provide detailed descriptions of the charging and other systems being installed.
The web page describes the rewiring. There is a lot of information separated into the following sections.
Wire Sizing
| AWG wire gauge ampicity and resistance in milliohm per foot | ||||||||||
| AWG | current | resistance | AWG | current | resistance | AWG | current | resistance | ||
| 2/0 | 231-330 | 0.08 | 6 | 84-120 | 0.40 | 12 | 32-45 | 1.75 | ||
| 2 | 147-210 | 0.16 | 8 | 56-80 | 0.62 | 14 | 25-35 | 2.53 | ||
| 4 | 112-160 | 0.24 | 10 | 42-60 | 1.00 | 16 | 18-25 | 4.00 | ||
A number of resource provide wire sizing information. The Blue Sea ABYC Ampicity Rating Table is a reprint of the American Boat and Yacht Council (ABYC) recommendation for minimum wire size to safely carry a current load. The Ancor catalog provides ABYC recommended wire colors (which we will ignore) and the often cited or reprinted tables of conductor size for 10% or 3% voltage drop. More useful is the table of AWG Wire and Cable Specifications. Using this table, the exact voltage drop and power loss can be computed for a given wire length and current.
An excerpt table is provided, giving the ABYC Amp rating for wire with 105°C insulation (Ancor marine wire) that is not exposed to the heat of an engine room (we no longer have a diesel engine). A current range is given for bundled wires and unbundled. This range takes into account variations in air flow around the wire and inability of heat to escape the wire due to bundling.
The four parallel 48V battery modules will each have a separate AWG #2 gauge wire from the module positive side to the 48V load bus bar and a separate AWG #6 gauge wire from the 48V module positive side to the charge side bus bar. With one module each, no bus bar is needed for the 24V or 12V bank. The 24V and 12V modules will also have AWG #2 gauge wire from the module but connect directly to a load side breaker and WG #6 gauge wire from the module to the charge side ProStar charge controller.
The 48V bank will require AWG #2/0 load side wire from the 600A bus bar where the 48V battery modules are connected in parallel to the battery switch for the motor and in the future to the circuit breakers for the galley stove inverter. The 24V and 12V banks can use AWG #2 load side wiring. A common 600A ground bus bar will serve all three battery banks. AWG #2/0 wire will be used for all wires used to connect the 48V bus bar to the fuse, the battery switch, the shunt, and then to the motor power terminals.
Wires from the 48V load bus bar to the breakers will be AWG #2/0. Wires from the 24V or 12V battery to the breakers will be AWG #2. Wires on the load side of the breakers will be AWG #6 for all breakers of 50A or less or AWG #2 for breakers greater than 50A. All feed side wires (5) to the cabin mounted breaker panel assembly will be AWG #6. The cabin mounted breaker panel assembly load side wires to the terminal blocks behind the breaker panel will be AWG #10, except loads with 30A breakers (water heaters) or 50A breakers (small inverters) which will be AWG #6.
Wires to the large inverter used for the electric galley stove will be AWG #2 or AWG #2/0 (if we have enough #2/0 left over). The AC/heat inverter and water heaters will use AWG #6 wire. The smaller inverters for the galley and vanity AC sockets will use AWG #6 wire.
All other loads are connected to 15A or smaller breakers and will use AWG #10 wire to the terminal block nearest the load and then a fuse in some cases and the size wire used by the load if smaller to the load itself. For loads with short wires a butt connector and either AWG #10 or AWG #14 wire will be used, appropriately sized for the butt connector. LED lights or other low current loads using smaller than AWG #16 wire will use step down butt connectors to bring the wire size up to AWG #14.
Battery Charge and Load Wiring
There are three battery banks: 48V, 24V, and 12V. Each has a charging side and load side so that the charging and load can never be connected together without a battery. Details on the battery installation plan and battery wiring can be found on the Battery Installation Plan web page. Details on the charge controllers can be found on the Charge Controllers page.
The high current charging and loads will be handled with bus bars, battery switches, and battery protectors. The battery protectors shut off when a low battery voltage is detected and turn back on when battery voltage recovers, with some hysteresis in the voltage threshholds. The 24V and 12V load side bus bars and battery protected bus bars will be connected to the electrical panel for distribution to sets of lower current loads.
Bus bars and primary charge and load wiring
A total of eight load buses will be used, designated by voltage and priority. The priorities are LSOC for loads available at any state of charge, MSOC for loads that will become unavailable when battery protectors sense low battery voltage, and HSOC (high voltage) for loads that are only available when the battery has a relatively high state of charge. Only 12V has a MSOC. The bus bars are 48V LSOC, 48V HSOC, 24V LSOC, 24V HSOC, 12V LSOC, 12V MSOC, and 12V HSOC. In some cases where there is a single load for a given designation that load may be connected to a battery switch or battery protector directly rather than using a bus bar.
Each battery module will have separate charge and load ground cables. There are six modules, so 12 ground cables from the batteries. Two or three 600A x 4 bus bars will be used. Grounding is discussed in greater detail in the Grounding and Bonding section.
48V Charging Bus
Each battery module will also have a charging and load positive side. The four 48V modules charging positive cables will lead to a 150A x 4 48V charging bus bar. Also connected to this bus bar is a battery switch labeled "48V charging" and second 48V charging bus bar where the two solar panels, wind generator when installed, and AC charger will be connected.
Each charging source will be separately fused. Each source will have a separate charging shunt to allow monitoring of the individual charging sources. Each of the solar panels will be connected to a separate charge controller. The difference in solar panel outputs should provides insights into the effects of shading on the panels.
| Major Loads and Panel Feeds | |||
| V | A | type | desription |
| 48V | 250A | Class-T Fuse | auxilliary propulsion electric motor |
| 48V | 30A | Series 285 breaker | solenoid and 24V charger |
| 24V | 100A | Series 285 breaker | 150A bus bus for 24V total loads |
| 24V | 50A | Series 285 breaker | 24V total load bus bar to 24V LSOC panel feed |
| 24V | 50A | Series 285 breaker | 24V total load bus bar to solenoid and 24V HSOC feed |
| 24V | 30A | Series 285 breaker | 24V total load bus bar to solenoid and 12V charger |
| 12V | 150A | Series 285 breaker | 150A bus bar for 12V total loads |
| 12V | 50A | Series 285 breaker | total load bus bar to 12V LSOC panel feed |
| 12V | 50A | Series 285 breaker | total load bus bar to solenoid and 12V MSOC panel feed |
| 12V | 100A | Series 285 breaker | total load bus bar to solenoid and 12V HSOC panel feed |
| future | |||
| 48V | 120A | Series 285 breaker | solenoid and inverter for stove (when installed) |
| 24V | 80A? | Series 285 breaker | direct to windlass switch and windlass |
48V Load Bus
The 48V module load positive cables will be lead to a 600A x 4 bus bar. Also connected to this bus bar will be a a battery switches and a 40A circuit breaker. The battery switch will be labeled "48V load". The circuit breaker will be labeled "24V charging". The 48V load switch will only be connected to a fuse and then the auxilliary propulsion motor at this time. The 24V charging breaker will be connected to a battery protector and then Morningstar Prostar 25A MPPT charge controller, then the 24V charging single positive battery cable.
24V Load Bus
The 24V battery bank (single module) positive load side will be connected to a 150A circuit breaker labeled "24V load". The load side of the breaker will be connected to a shunt and then a fuse and bilge pump switch and a 150A bus bar and labeled "24V battery load". This bus bar will be connected to breakers for 24V high priority loads, 24V low priority loads, and 12V charging. The low priority breaker will have a solenoid to cut off loads when battery state-of-charge is low. Both priority load feeds will be connected to the cabin mounted breaker panel assembly. The 12V charging circuit breaker will be connected to a shunt, a solenoid, and a Morningstar Prostar 25A MPPT charger and then the single 12V battery module charging side cable.
12V Load Bus
The 12V battery bank (single module) positive load side will be connected to a 150A circuit breaker, a shunt, then a fuse and bilge pump switch and a 150A bus bar and labeled "12V load". Connected to the bus bar will be three circuit breakers for 12V high, medium and low priority loads. The medium and low priority loads will connected to solenoids. All three priority load feeds will be connected to the cabin mounted breaker panel assembly.
Major Load and Panel Feed Breakers
Major individual loads and the breaker panel feed lines will be supported by Blue Sea Systems 285-Series Circuit Breakers which are 25-150A thermal breakers rated for 48V use. These have studs for ¼" ring terminal connectors.
Shore Power AC Charging
Shore power will be connected only to a 48V charger. This provides isolation from badly grounded or improperly polarized shore power. This avoids an all too common source of galvanic corrosion problems and safety issues.
Connecting loads directly to shore power is not an option if some of the loads can exceed the shore power connector rating. For example, an electric stove can draw up to 4.9kW of power. Full power is over 20A at 230V or over 40A at 115V. A 120V 30A shore power connection could provide a little more than ⅓ of that power. A better solution is to provide multiple inverters, near the loads, for stove, galley appliances, vanity, and an heat/AC load. This avoids 115V wiring runs which if leaking due to contact with seawater could endanger crew.
The selection of a shore power charger is described in the Shore Power Charger section of the Battery Charging Plans web page.
Electrical Panel and Breakers and Fuses
The existing enclosure will be used if possible but with updated circuit panels. The 24V and 12V banks complicate the panel layout. A single positive bus can't be used. The NAV switches, anchor light and overall circuits such as cabin lighting, domestic water, water heaters and instruments will be controlled by switches on the panel. Finer fusing on loads will be accomodated by individual fuses or breakers located closer to the load.
Electrical Panel Enclosure
The panel will be simplified but may fit within the existing enclosure. Mystery switches, such as "Loran" will be eliminated. Loads installed by previous owners that bypass the panel such as VHF will be put on the panel (for example, VHF would be connected to "instruments" on the panel but have its own fuse).
The electrical panel enclosure is a teak shallow box with a 17" high by 10" wide openning and is mounted on the port side above the ice box. It is hinged for access to the wiring with the hinge on the port side. Wiring behind the panel is tight. It is set up for two batteries with an A, B, A+B switch and analog voltmeter. The battery switch and meter takes up a lot of room and the battery switch requires bringing battery cables into the box. There is very limited room behind the box for wiring. The cabinetry slopes back at the bottom so the panel is deeper at the bottom. This creates a head strike hazard when accessing the ice box.
The current wiring is spagetti. None of the wires are routed near the hinge, including the battery cables so the box can barely be openned. Many of the wires are too small for the breaker size.
Currently there are only hole saw cutouts for the wires. Depth may be an issue on the shallower upper part but the existing enclosure. The cabinetry will be cut out behind the circuit panel box to improve depth and reduce wire bends.
A new teak enclosure may be made with a constant depth rather than sloping and deep toward the bottom. If so, the new enclosure will be ½" to 1" wider to allow cables a greater bend radius at the hinge and making it easier to open the enclosure for access to the wiring.
Electrical Panel Wiring
Due to the use of 24V and 12V battery banks and circuit groups prioritized using battery protectors, multiple panels will be used. The battery switches will be located elsewhere and no analog meter will be used.
Blue Sea makes two small panels with two columns of breakers, with LED indicators on each breaker. Both are rated for 12v or 24V. Each column has a separate bus bar. The Blue Sea 8096 has two columns of three rows each for six total breakers. Dimensions are 10½" wide by 3¾" high. The panel overlaps by ¼" on each side and top and bottom so requires a 10" wide by 3¼" high cutout. The Blue Sea 8385 is similar with four rows for eight total breakers and is 4½" high. Both are 2½" deep.
The existing enclosure can fit two each of the Blue Sea 8096 and Blue Sea 8385 with ½" to spare vertically. There is a chance that width will be an issue with the existing enclosure and require that a new enclosure be used.
Many panels are wired with both positive and DC ground with per circuit DC ground wires from the panel. In some cases this serves a purpose, avoiding having the positive and DC ground wires taking different paths and potentially creating a magnetic field which could affect the compass.
In this case the panel is separated from the very large area behind it by a small gap between the bridgedeck seat and interior cabinetry. Not bringing grounds through this restricted space means positive feed current passes about 18 inches to the panel, then 18 inches back without corresponding ground current. Since the panel wires themselves are close together and in parallel no significant magnetic field should result.
A set of terminal blocks will be placed in the area behind the breaker panel. A total of 28 wires from the panel (number of breakers including spares) to ring terminals and to these terminal blocks. From these terminal blocks the loads will be bundles into common runs to the various parts of the boat where the loads reside. A ground bus bar can be placed in the area behind the panel. Rather than individual ground wires, a larger ground distribution wire can be run in parallel to feed runs to avoid creating magnetic fields. The Cabin Wiring section provides further details.
Inverters
Some loads are only available as 115 VAC or 230 VAC products. Most notable is electric galley stove, a roughly 5kW load. All but a few very expensive AC/heat cabin heat exchangers only come in 115 VAC or 230 VAC versions. The smaller AC/heat units draw well under 1000kW. The other loads are small kitchen appliances and bathroom appliances that only come in 115 VAC (in US, mostly 230 VAC in Europe).
To eliminate the potential danger of AC wiring it is best to put inverters near the loads and use the lower voltage DC wiring to distribute power. The galley and stove are close to each other. The vanity would require a long run to reach the galley.
The larger inverters and inverter/chargers have higher power draw when idle than the smaller units. The range is 5W - 20W when idle. For this reason inverters should be shut off when not in use. If possible breakers on the circuit panel should be used. This favors smaller inverters with the added benefit that these smaller inverters generally have a set of GFCI outlets and a power switch on the inverter itself.
An inverter (or inverter/charger) large enough to support the stove would have to be installed out of the way but in a ventilated area and not near potential water intrusion. A lighted switch near the stove can be provided, using a high amperage solenoid to enable the stove. The lighted switch should be bright enough to serve as a warning that the inverter is enabled, even if the stove is not in used. Some inverter/chargers have provisions for a remote on/off switch, eliminating the need for a solenoid Some large inverter/chargers provide an output designed for a small external fan or a fan solenoid.
breaker and inverter selection
Inverters require high amperage breakers since they must be sized to the largest load they could reasonably encounter. The circuit panels can take a replacement Blue Sea A-Series Circuit Breaker but these only come in up to 50A. If an inverter is to be connected to the breaker panel, then a 12V inverter is in practice limited to 500W (assuming a possible voltage drop and some inefficiency). By the same reasoning, a 24V inverter connected to a 50A breaker is limited to 100W. Using a 150A breaker outside the panel 1500W could be supported at 12V, 3000W at 24V, or 6000W at 48V.
Xantrex provides a handy Power Inverter Comparison Chart with all of their marine inverters listed. Many retailers, such as Defender, only carry a selection of the 12V versions but the 24V versions can be special ordered. The Xantrex PROwatt 800 24V is particularly well sized for 24V use with a 50A breaker. It is capable of 800W continuous, and 1000W for 10 minutes. It has a (larger) internal breaker plus thermal protection.
For larger loads, the Xantrex Prosine 1800 (806-1850) is rated at 1800W continuous 2900W brief surge. A 100-120A circuit breaker would be appropriate.
Another source of inverters is ProMariner. The ProMariner Inverters come in 12V only in 400W to 2000W versions. The ProMariner Modified Sine Inverter/Charger models come in 12V and 24V versions, with 24V versions of 1500W and 2500W. The ProMariner Pure Sine Inverter/Charger models come 12V or 24V but are 2000W only. The charger in the inverter/charger models add cost for a feature that won't be used.
Magnum Energy offers a selection of 24V and 48V inverters. The CSW Series 2000W 24V Pure Sine Inverter is their smallest 24V marine inverter. The N Series Pure Sine inverters come in a variety of sizes from 400W to 5600W. These are ventless (cabinet vents only reach heat sinks, electronics are not vented) and suitable for marine use. Very few 48V inverters are available and at low power. The MS Series Inverter Charger have a 48V 4000W 48V charger. The 60Hz inverters are available in 120V only.
The 5kW requirement for all burners and oven on an electric galley stove requires using an inverter/charger, even though the charger adds cost and is not needed. A 4kW rated inverter charger may be suitable for use with a electric galley stove if only some of the burners and the oven are used simultaneously. The Magnum Energy MS Series 4000W 48V Pure Sine Inverter/Charger is one such product. The 24V version is available through Defender and so the 48V version could be special ordered. The Xantrex Marine Inverter/Charger Comparison Chart lists only 12V versions. Outback Power product line is available through many solar distrubutors. Many of their products are suitable for marine use. The Outback FXR/FXVR Series includes the VFXR3648A is rated at 3600W continuous, 4000W for 30 minutes but must be installed in a dry environment. The sealed FXR3048A is rated at 3000W continuous and 3200W for 30 minutes. The Outback M Series VFX3648M and FX3048MT are the marine versions and are harder to come by but very well suited for this use.
The Magnum Energy MS Series (48V) and Outback FX3048MT are series stackable for 230V operation with two units. This could deliver 6kW to 8kW continuous to the stove but require two breakers. This is a high cost solution. It may be difficult to install due to the space requirements and ventilation needs. The 24V versions are also series stackable but while two 24V inverters could be used with two 120A to 150A circuit breakers on the 24V bank this would be too much current for the 24V battery bank itself.
air conditioning and heat
The two AC/heat units being considered are Mabru MPS SC4.2K BTU 115V 60Hz with copper fins and the Webasto FCF Platinum 6000 BTU 115V 60Hz. Both consume under 5A at 115V (575W) when running, though starting current can be very high, up to 22A (2.5kW) for 142 msec with the Webasto and unstated for the Mabru. The ProWatt 800 inverter is rated for 2000W surge and so ma be inadequate for the start up load. The Xantrex Prosine 1800 (806-1850) or Magnum CSW Series 2000W 24V Pure Sine Inverter would handle this load but the surge could trip a 24VDC 50A breaker. The Blue Sea A-Series 7230 50A breaker provides a chart and it appears this 300% load can be tolerated for more than 100 msec and perhaps 200 msec or more.
If a 50A breaker trips too easily, then C series breakers can be used. The C series 7246, 7248, and 7250 breakers are rated at 60A, 80A, and 100A respectively. The panel bus is limited to 100A. The C series breaker can be mounted in the panel or separately. If mounted in the panel, the load breaker prior to the panel might have to be increased, though the series 285 thermal breakers are slow to react and so would not be as affected by a high turn on transient. A C series breaker can be mounted in a Blue Sea 8072 single pole mounting panel providing a breaker in the cabin.
cabin inverters
With the exception of an electric galley stove the cabin inverter loads are primarily low power loads and with few exceptions do not have turn on transients at all. Some kitchen appliances with motors such as a blender or mixer would pose small turn on transients.
gimballed galley stove
The selection of marine gimballed galley electric stoves may be limited to the Force 10 three burner electric gimballed stove. A line of galley cooktops and ovens suitable for marine use is available from GN Espace yacth galley systems in the UK but my not be available in the US. The GN Espace brochure provides a concise introduction to the products they offer.
Each burner of the Force 10 stove is 1200W and the oven is 1300W for a total of 4.9kW. The cooktop on this unit has been upgraded to a glass top. The model 65336 is the 240V version. With a suggested AC breaker size of 20A, this is just under 5kW. The breaker and inverter selection section provides details on which marine inverters would be appropriate to handle the electrical load. The bottom line is either the Magnum Energy MS Series 4000W 48V Pure Sine Inverter/Charger or Outback FX3048MT using two inverters in series stack mode.
galley outlets
The galley is small. Two outlets should be enough. The most often used appliance would be a coffee grinder and a 4 cup coffee maker or something to heat water for a french press. Some other appliances might be a blender or immersion blender, and space permitting one or more of slow cooker, small toaster oven, or small microwave. Most of these can be run individually using a Xantrex PROwatt 800 24V inverter. A larger inverter could be used either limited to 1200W by a 50A breaker or using a Blue Sea Series C breaker mounted outside the breaker panel as described in the air conditioning and heat section.
vanity AC outlets
The vanity AC outlets are not expected to need much power. Normal use is charging an electric toothbrush or electric razor. A guest might bring a hair blow dryer. This could draw 1200-2000 watt. It might be worth banishing people with high power blow dryers (if hair styling is that important, do you really want to know them?). A 12V inverter would only be able to support 500W and maybe 600W. The Xantrex PROwatt 800 24V provides an expensive solution that could support 800W continuous, 1000W for 10 minutes. There are many inexpensive 12V solutions but limited to 500W.
Cabin Wiring
The Battery Charge and Load Wiring and the Electrical Panel and Breakers and Fuses sections describe the power distribution to major loads or to the breaker panel and the layout of the breaker panel. Feeds to the breaker panel are designated 24V high and low priority, and 12V high, medium and low priority. There are four Blue Sea breaker panels, with 6, 8, 6, and 8 breakers each top to bottom and respectively support 6 12V high priority, 8 12V medium priority, 6 12V low priority, and 4 each 24V high and low priority. The panel wiring is difficult to access and therefore led back to a set of terminal blocks in the area behind the breaker panel, with a total of 28 terminals pairs.
From the area behing the breaker panels, wires will be routed aft forward, to systems in the same area, or over to the starboard side and then forward. Wire run aft go to the stern, the steering pedestal or steering pedestal bars, and to the mizzen mast. Wires run forward go to the port water system, the galley, the bilge, the main mast, the main cabin, the fore cabin, or the bow. Wires run to the starboard side, then forward run to the port side water system and the navigation station. Some of the circuits are run to multiple places. For example the navigation lights circuit runs to the stern, the bow, and to the steering pedistal for the compass light. The same circuit could also run courtesy lights.
Cabin positive load wiring will primarily use Ancor Marine Grade Primary Wire - 10 AWG purchased in 100 foot spools in white, red, and yellow. The white will be used for 24V loads, and the red for 12V loads. Ground wiring will primarily use AWG #2/0, AWG #2, or AWG #6 black cable as distribution to places with multiple loads, then distributed to individual loads with AWG #10 yellow wire.
The breaker panels come with 15A breakers. Some may be replaced with up to 50A breakers. All wires from the breakers to the terminal blocks will use AWG #10 wire with Anchor AWG #10-12 ring terminals with heat shrink on each end. With 28 circuits the panel to terminal block alone uses 56 of these so a 100 pack for #8 screws and 25 pack for #10 screws was initially purchased. For smaller loads with existing wiring AWG #14-16 ring terminals for #8 screws will be used. For
One Blue Sea 65 Amp 4 Circuit Terminal Block will be used for any circuits off the panels with over 30A breakers. The remaining terminal blocks behind the panels will be one Blue Sea 30 Amp 8 Circuit Terminal Block for the 12V medium priority loads, two Blue Sea 30 Amp 6 Circuit Terminal Blocks for the 12V high priority and low priority loads, and two Blue Sea 30 Amp 4 Circuit Terminal Blocks for the 24V high priority and low priority loads.
Terminal blocks will be used in places where many circuits are routed or where circuits are routed through difficult spaces. These are likely to be Blue Sea 20 Amp Terminal Blocks where loads are 20A or less.
Load wiring will be primarily white for 24V, red for 12V and black for ground. To identify wire for individual circuits at terminal blocks and periodically along wire runs, colored electrical tape will be used. With no engine room heat, tape is not expected to get hot enough to soften the glue and the consequence of losing a piece of tape is more an annoyance than a problem. Circuits will be numbered, expressed as a three nibble hexidecimal number. A base four system of with four tape colors will be used to mark the wires. A hex digit is two nibbles and takes two tape stripes to represent. The top nibble, 0-3, is the circuit panel, 12V hi pri, 12V med pri, 12V low pri, 24V. This first tape stripe will be wider than the others to tell which way the number is read. The rest of the number is the circuit panel position, numbered up and down on the left column first, then the right, starting at zero. The colors are green, yellow, purple, and gray. These colors provide contrast with red, white, and black wire.
The following table lists the circuits by destination. Note that any given circuit (such as navigation lights) may go to multiple destinations.
| Circuits listed by destination of the circuit | ||||||
| Where | Circuit | Num | Mark | Feed Group | Amps | Description |
| stern | nav lights | 0x03 | 12V high pri | 15A | Less than 5A with LED lights. Goes to stern, bow, compass light, likely some courtesy lights. | |
| autopilot | 0x31 | 12V high pri | 4A | The Type 1 drive unit (EV-2 system) consumes 18-36W or 1.5-3A at 12V. The Type 2 drive unit (EV-4 system) consumes 48-72W or 2-3A at 24V. The EV-2 autopilot is not available in 24V, only the EV-4 system which is oversized but comes in 24V. | ||
| steering | nav lights | 0x03 | 12V high pri | 15A | Less than 5A with LED lights. Goes to stern, bow, compass light, likely some courtesy lights. | |
| instruments | 0x01 | 12V high pri | 15A | The instruments circuit provides power to the multifunction display, speed/depth transducer, and wind transducer. | ||
| mizzen | spreader lights | 0x20 | 12V low pri | 5A | Spreader lights will be added and so will be LED and well under 5A total. | |
| radar | 0x30 | 24V high pri | 5A | Actual power consumption is 17W or less than 1A at 24V. | ||
| systems | cockpit lights | 0x11 | 12V med pri | 5A | Cockpit lights will be switched in the cockpit and should be under 1A with white courtesy, red lighting, and white lighting. Some red courtesy lights will be connected to the nav circuit. | |
| storage lights | 0x12 | 12V med pri | 5A | The storage light circuit will lead to switched lighting in the engine (motor) compartment, storage portions of the sizeable aft bilge area, and switched lighting for wiring, breakers, and systems in this area. | ||
| gray water | 0x13 | 12V med pri | 10A | Multiple gray water tanks and pumps serve the refrigerator drain, galley drain, vanity drain, and shower drain. | ||
| audio system | 0x25 | 12V low pri | 20A | The old audio system was located above the pilot berth. The system is capable of driving a lot of power to up to four speakers. | ||
| refrigeration | 0x32 | 24V high pri | 5A | The refrigeration system should consume under 5A. | ||
| watermaker | 0x35 | 24V low pri | 5A | The watermaker, when installed, should consume under 5A. | ||
| nav station | nav station | 0x00 | 12V high pri | 5A | The navigation station will have some switched lighting plus some displays to monitor instruments or systems. | |
| instruments | 0x01 | 12V high pri | 15A | The instruments circuit provides power to the multifunction display, speed/depth transducer, and wind transducer. There may be a display or raymarine hub which is switched off in the nav station if instruments are not enabled. | ||
| cabin lights | 0x10 | 12V med pri | 5A | Cabin lights are thought to be all LED which should consume well under 5A. | ||
| 12V sockets | 0x21 | 12V low pri | 15A | Sockets will be fused for 15A (or the current limit of the sockets if lower) but will primarily be used for USB charging and so draw under 1A in normal use. | ||
| starboard | forw pump | 0x15 | 12V med pri | 5A | The forward cabin fresh water pump is located under the settee on the starboard side. | |
| forw heater | 0x24 | 12V low pri | 25A | The forward cabin fresh water heater is located behind the starboard settee aft backrest. | ||
| port | galley pump | 0x14 | 12V med pri | 5A | The galley fresh water pump is located under the settee on the port side. | |
| galley heater | 0x23 | 12V low pri | 25A | The galley fresh water heater is located behind the port settee aft backrest. | ||
| galley | cabin lights | 0x10 | 12V med pri | 5A | Cabin lights are thought to be all LED which should consume well under 5A. | |
| gray water | 0x13 | 12V med pri | 10A | Multiple gray water tanks and pumps serve the refrigerator drain, galley drain, vanity drain, and shower drain. | ||
| 12V sockets | 0x21 | 12V low pri | 15A | Sockets will be fused for 15A (or the current limit of the sockets if lower) but will primarily be used for USB charging and so draw under 1A in normal use. | ||
| galley inverter | 0x36 | 24V low pri | 50A | A 50A breaker can support 1200W but 24V inverters are hard to come by. If a larger breaker is needed, then the breaker will be located in the galley near the inverter. | ||
| bilge | 12V bilge pumps | -- | 12V | 5A each | Two bilge pumps will be located in the main bilge, one 24V high capacity and one 12V (existing). One 12V bilge pump will be located in the forward bilge area. These connections will bypass the breaker panel but lead to small individual breakers and bilge pump switches. | |
| 24V bilge pump | -- | 24V | 5A | Two bilge pumps will be located in the main bilge, one 24V high capacity and one 12V (existing). One 12V bilge pump will be located in the forward bilge area. These connections will bypass the breaker panel but lead to small individual breakers and bilge pump switches. | ||
| mast | instruments | 0x01 | 12V high pri | 15A | The instruments circuit provides power to the multifunction display, speed/depth transducer, and wind transducer. There may be a display or raymarine hub which is switched off in the nav station if instruments are not enabled. | |
| nav lights | 0x03 | 12V high pri | 15A | Less than 5A with LED lights. Goes to stern, bow, compass light, likely some courtesy lights. | ||
| steaming | 0x04 | 12V high pri | 5A | The steaming light is mounted on the front of main mast. If it is not currently an LED light it will be replaced with an LED light. | ||
| anchor light | 0x05 | 12V high pri | 5A | The anchor light is mounted on the top of main mast. If it is not currently an LED light it will be replaced with an LED light. | ||
| spreader lights | 0x20 | 12V low pri | 5A | Spreader lights will be added and so will be LED and well under 5A total. | ||
| cabin | cabin lights | 0x10 | 12V med pri | 5A | Cabin lights are thought to be all LED which should consume well under 5A. | |
| gray water | 0x13 | 12V med pri | 10A | Multiple gray water tanks and pumps serve the refrigerator drain, galley drain, vanity drain, and shower drain. | ||
| AC/heat | 0x34 | 24V low pri | 50A | It might be that more than a 50A breaker is needed to handle the turn on surge. If that is the case a Series C breaker is needed and that would be mounted in the cabin. | ||
| vanity inverter | 0x37 | 24V low pri | 50A | A 50A breaker can support 1200W but 24V inverters are hard to come by. An 800W or 1000W inverter should be sufficient for the vanity unless a guest plugs in a blow dryer. | ||
| bow | nav lights | 0x03 | 12V high pri | 15A | Less than 5A with LED lights. Goes to stern, bow, compass light, likely some courtesy lights. | |
| washdown | 0x22 | 12V low pri | 5A | A washdown pump is available with switch and hose in the chain locker. | ||
Grounding and Bonding
Grounding and bonding are not the same thing. Most boat owners and some professionals who install boat wiring don't adequately understand marine grounding and bonding. Some good sources of information can be found online. One, though quite old, is a Marine Surveyors Association article on electrical systems with good coverage of the topics of grounding and bonding. West Marine has republished some articles that originally appeared elsewhere, such as Practical Sailor. One is Marine Grounding Systems Nigel Calder's book "Second Edition, Boatowner's Mechanical and Electrical Manual" is a comprehensive reference that includes electrical wiring and grounding and bonding considerations.
DC Ground Wire Sizes
The wire sizes for the battery module ground wires will be the same as size of the battery module positive side for that module, AWG #2 gauge wire for load side and #6 gauge wire for charging side. Each module has a load side and charge side grounding wire and so a small grounding loop is formed. A grounding bus bar will be near the modules to reduce the size of this loop and the load and charge grounding wires may be twisted together to reduce induction effects. Wires from the load side ground bus will be AWG #2/0. Ground wires will be led to distribution bus bars and sized appropriately for the loads to that distribution bus. These will be AWG #2/0 for total loads of over 150A, AWG #2 for loads of over 50A to 150A. For total loads of 50A or less AWG #6 will be used. The total load will be assumed to be the sum of the circuit breakers on the positive side.
Corrosion and Electrolysis
Corrosion of underwater metals can occur due to galvanic effects or electrolysis. The two are different.
Galvanic corrosion occurs where dissimilar metals are in the water and a current can flow between them, usually due to bonding. Sacraficial zinc anodes are used so that the metal being eaten away is always the zinc and the bronze, stainless steel, and aluminum is protected.
Electrolysis occurs due to stray currents. For example, if two pieces of metal are grounded but a corroded connector in the ground wiring between the two is causing a high resistance, then a voltage difference is created whenever a current is passed through that ground circuit.
Isolating DC Ground and AC Ground
An old approach, now discouraged, was to connect DC ground, AC ground, and all bonding together. This can have disasterous consequences due to undersized wire or corrosion leading to leakage to the DC and AC ground. On land grounding the AC to the actual ground is considered a safety requirement. With today's GFCI built into inverters and GFCI outlets and in newer boats complete system equipment leakage circuit interrupter (ELCI) this is no longer the case.
AC grounding and DC grounding are separate systems and should be floating. The AC can be grounded to the shore power for loads that can be connected to shore power. In this case only the shore power battery charger is connected to shore power and so the shore power ground wire and the hot and neutral are connected to this charger but no where else. This avoids problems due to faults in the dock or marina wiring.
The DC ground is common among the 48V, 24V, and 12V DC systems but otherwise floating. These could also be independent but there is little or no risk in interconnecting them.
Bonding
Traditionally the bonding system, usually a green wire, attaches all underwater metal together. The bonding system should not be connected to any ground wires and then putting zinc sacraficial anodes on some metals such as props, shafts, and other mechanical systems in the water.
Bonding of underwater metals is no longer recommended. The issue with bonding is that a stray current through the water due to other boats, dock, or marina fault creates a voltage difference in the water itself. At some marinas this occasionally gets bad enough to electrocute swimmers. If two pieces of metal are connected together through bonding and there is a voltage difference in the water, one of those will corrode quickly.
Using an engine block as a DC grounding bus bar is one of the worst bonding offenses. It is unfortunate that many starter motors and (fewer) alternator assume that the DC ground will be the engine block. Another problem is that the engine and propeller shaft are coupled with an all metal coupling. Couplings are available which electrically isolate the shaft and the engine.
The electric auxilliary being used electrically isolates the shaft from the motor. This makes it easier to keep DC ground and bonding separate. Since bonding is not used electrolysis cannot occur. Not bonding the through hulls and seacocks means that the bronze is on its own, not protected by prop zinc anodes. This has been the case for the boat's lifetime and there has been no evidence of galvanic corrosion.
Lightning Protection
Bonding for the purpose of lightning protection is still recommended. Bonding the masts to the keel and then using a charge disipator at the top of each mast can prevent most but not all lightning strikes. Making a boat survivable in the event of a lightning strike is more difficult. It involves creating a Faraday cage where the lightning flows around the boat.
One way to create a Faraday cage is to bond the chainplates to the keel. The stainless steel stays are not good enough conductors. This risks melting and snapping a stay under load and dismasting. A better solution is to use an installed as needed Faraday cage. A tall pig stick on each mast can be used to raise a set of AWG #8 wires, preferable bare wires, held outboard and dropped into the water with 1-2 sqft copper plates in the water. One at the bow and one at the stern and at least one pair outboard of each mast creates an effective Faraday cage, but takes forsight and some work to install when lightning is threatenning.
RF Grounding
RF systems benefit from a good RF ground and SSB (or HAM) tranceivers absolutely require a good ground plane. A typical ground plane is copper tape inside the hull from the stern to the keel bolts, using the metal keel as a ground. A capacitor should be used as DC isolation of the ground plane while passing the RF signal. A common recommendation is to cut the copper tape and leave a small gap bridged by a set of small capacitors soldered to the tape. This gap also better isolates the antenna tuner from a lightning strike.
When an SSB is installed, I will very likely have the antenna and RF ground professionally installed or at least seek professional advice. With any luck Space-X Starlink will be available and SSB will go the way of Loran but that remains uncertain.